34. Pleural Space

Question 1

Name the different component parts of the pleura

Answer 1

Visceral

Parietal

• Costal
• Diaphragmatic
• Mediastinal

Question 2

Provide 2 reasons why pleural fluid appears different in VD radiographs vs DV

Answer 2

1) Effaces the heart as surrounds it
2) Fluid forms DEEPER pocket, so increased opacification of thorax

Question 3

Table - Causes of pleural fluid (trans / mod / ex)

Answer 3

Question 4

What volume of pleural fluid, in a medium sized dog, is required for widened interlobar fissures?

Answer 4

100ml

Question 5

Which radiographic views are best for SMALL volumes of pleural fluid?

Answer 5

VD -> more likely to enter fissure rather than sit over sternum

Lateral -> see fissures, obscure cardiac silhouette

Question 6

In which projection may blunting of the costophrenic junction be visualised?

Answer 6

VD -> Fluid accumulated between diaphragm and lung dorsocaudally

Question 7

What DDx should be considered if asymmetric pleural fluid is present?

Answer 7

• Pleuritis-> closed mediastinal fenestrations due to inflammation / mass
• Pleural fibrosis -> chronic fluid, inflammatory fluid => typical rounded appearance to lung
• Intact mediastinum
• PYOTHORAX -> viscus / encapsulated fluid.
• Differential lung compliance

Question 8

What radiographic feature should prompt consideration of pleural fibrosis?

Answer 8

Rounding of a lung lobe

Question 9

What is the significance of concurrent pleural and peritoneal fluid?

Answer 9

• Typically indicator of severe disease

32/48 dogs had either neoplastic / CV disease

Question 10

Which views tend to be best for seeing pneumo?

Answer 10

Laterals (cf opposite of fluid, first seen in VD)

Question 11

List 4 DDx for pneumothorax

Answer 11

• Tear in lung involving visceral pleura
• Thoracic wall rent
• Extension of pneumomediastinum
• Rupture of cavitary lung mass

Question 12

What is an early sign of pneumo?

Answer 12

Gas bubbles by cardiac apex in LATERAL

Question 13

What radiographic technique is described to help visualised small pneumo?

Answer 13

Horizontal beam, lateral -> Aim at sternum. Air accumulates non-dependent thoracic wall

High sensitivity

Question 14

Which views are considered best for visualising pneumo?

Answer 14

Lat

Lat (horizontal beam)

(DV > VD)

Question 15

What proportion of dogs develop bilateral pneumo from unilater?

Answer 15

22/24 in experimental study

-> presence of unilateral => Same DDx as for fluid

Question 16

Features and DEFINITION of tension pneumothorax

Answer 16

• One way / check valve -> Increase in pleural pressures > atomspheric pressures.
• Lung collapse (and loss of shape as marked loss in volume)
• Mediastinal shift
• Diaphragmatic displacement caudally, with tenting

Question 17

Pitfalls with pneumo diagnosis?

Answer 17

• Elevation of cardiac silhoette: Microcardia, deep chested dog, hyperinflated lungs
• Skin folds